2205/X65双金属管道JCO成形有限元研究

目的研究2205/X65双金属管道JCO成形过程应力应变的演变及其影响因素。方法通过对2205/X65双金属管道JCO成形过程进行有限元模拟,分析了双金属管道成形后应力应变分布与演变情况,得到双金属板材自由弯曲变形特点及不同材料之间的界面应力分布特点,在此基础上研究了最大剪切应力随下压量、下模跨距以及模具半径的变化规律。结果 2205/X65双金属管成形后应力呈分段分布,除了最后一次下压位置,其他各段的应力大小和分布都是一样的,成形后的管坯由圆弧段和直管段相隔循环构成。2205/X65双金属管道成形后中性层在靠近屈服强度更大的2205一侧;在模具下压到最低点时板材上下表面屈服,中性层应力最小;卸载完成后管道厚度方向中间部位有最大残余应力分布,上下表面的环向应力都呈压应力分布。结论不同材料之间界面应力存在大梯度过渡,双金属板材弯曲成形中性层向一侧偏移。2205/X65双金属管道成形过程中最大剪切应力随着下压量的增大呈线性增大,当下压量为30mm时,最大剪切应力达到实验测试的双金属板材的剪切强度;随着下模跨距的增加,最大剪切应力不断减小;随着上模半径的增加,最大剪切应力不断增加,增加幅度较大;随着下模半径的增加,最大剪切应力不断增加,但增加幅度较小。成形后回弹角随着下压量的增大先减小再增大,最后趋于稳定。

Finite Element Study on JCO Forming of 2205/X65 Bimetallic Pipeline

The paper aims to study on the stress-strain evolution and influencing factors in the JCO forming process of 2205/X65 bimetallic pipe. Based on the finite element modeling of 2205/X65 bimetallic pipe JCO forming process, the stress-strain distribution and evolution of bimetallic pipe were analyzed, and the free bending deformation characteristics of bimetallic plate and the distribution characteristics of interface stress between different materials were obtained. On this basis, the change rules of maximum shear stress with the pressing amount, the lower die span and the die radius were studied. The stress of 2205/X65 bimetallic pipe showed segmented distribution after forming. Except for the last pressing position, the size and distribution of the stresses of the other section of the pipe were the same, and the pipe blank after forming was composed of circular arc section and straight section. The neutral layer of bending of bimetallic plate was closer to the 2205 side of higher yield strength; when the die was pressed to the lowest point, the upper and lower surfaces reached yield state, and the stress at the neutral layer was the minimum; after unloading, the maximum residual stress distribution was on the middle part of the pipe thickness direction, the hoop stress of the upper and lower surface showed compressive stress distribution. There is a large gradient transition in the interface stress between different materials, and the neutral layer of bimetallic plate is offset to one side of the plate. The maximum shear stress of the 2205/X65 bimetallic pipe increases linearly with the increase of the pressing amount. When the pressing amount is 30 mm, the maximum shear stress reaches the experimentally tested shear strength of the bimetallic plate. The maximum shear stress decreases with the increase of the span of the lower die, increases with the increase of the radius of the upper die, and increases with the increase of the radius of the lower die. The maximum shear stress increases with the increase of the radius of the lower die, but the increase amplitude is small. After the forming, the spring back angle decreases first and then increases and finally stabilizes with the increase of the pressing amount.